CHI-KUANG SUNLiang, J.-C.J.-C.LiangYu, X.-Y.X.-Y.Yu2018-09-102018-09-10200000319007http://www.scopus.com/inward/record.url?eid=2-s2.0-0001101377&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/289848https://www.scopus.com/inward/record.uri?eid=2-s2.0-0001101377&doi=10.1103%2fPhysRevLett.84.179&partnerID=40&md5=5e7eb2ac3289c6a4c4f16b33e3c2d1ffLarge coherent acoustic phonon oscillations were demonstrated using InGaN/OaN multiple quantum wells with piezoelectric fields. With UV femtosecond pulse excitation, photogenerated carriers screened the piezoelectric field and initiated the displucive coherent phonon oscillations. The specific phonon frequency was selected by the coupling between the periodic carrier distribution and the corresponding acoustic phonon mode. The induced acoustic phonon oscillation resulted in piezoelectric field modulation and then caused absorption variation through the quantum confined Franz-Keldysh effect. The wave vector uncertainty due to the finite sample width was found to determine the observed dephasing time.journal article2-s2.0-0001101377